Hopefully one of the folks smarter than I am can figure it out, but I suspect it's just some kind of bug. I got the same results you did when trying to change the 60 to 50, and also when trying to link them with an equation; however, when I deleted the 60 dimension and added an equal relation between the two arcs it worked fine.

Hopefully one of the folks smarter than I am can figure it out, but I suspect it's just some kind of bug. I got the same results you did when trying to change the 60 to 50, and also when trying to link them with an equation; however, when I deleted the 60 dimension and added an equal relation between the two arcs it worked fine.

Thanks Glenn

You replied while I was writing my second post, there's not many smarter than you!

From this sketch both types of equal relations on the arcs are suppressed. The top radius is set to driven, as is the height, yet the top arc is black, maybe it's just my monday brain, but surely this sketch should have more blue

I didn't apply an offset to either of the arcs only to the vertical line below them. I manually drew the the two offset arcs and merged their centre points with the cp of the corresponding other arc (two less points for the solver)

To get the tangent relation - I used a horizontal relation, and a coincident relation on a construction line, joining the shared arc vertex and the center points.

To get the arcs equal, I set the radii to driven and unsuppressed the equal relations.

Going this way is easy, the difficulty is returning to an unequal state.

I had to change something else to get the arcs to solve independently. Nudging the height (1730) while one of the dims was still driven worked - once the radii were slightly different the sketch could solve again.

This seems like a bit of a future nightmare to be honest, but I'm not sure of a good alternative.

Well, can you make them 2 separate sketches? 1 that ends at the end point of the first radius, and another that begins at the same point. Then you can control the end point of the first sketch and just make the 2nd sketch whatever you want it to be (you can control these then with Global coordinates (or equations)). Then, if you still need it to be all 1 sketch, then just create a 3rd sketch and convert entities to get it.